EP0082145A1 - Universal fluid level maintainer - Google Patents

Abstract

An automatic fluid level maintenance device detects the level of a fluid to determine if it is below a critical level and, if so, automatically ensures filling with fluid until the critical level of the fluid is restored. The device for automatically maintaining the level of a fluid (10) comprises a body (20), a probe (30), a threaded upper ring (40), a threaded bottom ring (50), a vent (60), a mounting bracket (70), a flexible hose (80), a first airtight tube (81), and a second airtight tube (82). The fluid level maintenance device (10) cooperates with an upper airtight reservoir (90) (or supply reservoir) and a lubrication enclosure, an oil sump, or other type of lower reservoir. fluid (100). The lower end of the probe (30) is adjusted to be at a desired operating level (90). When the fluid level in the lower reservoir (100) falls below the tip of the probe (30) in the body (20), the fluid from the upper reservoir (90) flows downward down through of the body (20) in the lower reservoir (100). When a sufficient quantity of fluid raises the level in the body (20) to cover the lower tip of the probe (30), the flow ceases.

Description

UNIVERSAL FLUID LEVEL MAINTAINER

TECHNICAL FIELD

The invention pertains to automatic fluid level maintainers and especially to fluid level maintainers that sense the level of a fluid to determine if it is below a critical level, and, if it is so determined, causes an automatic replenishment of the fluid supply until the critical level is restored. The invention is particularly adaptable for use in automotive vehicle crankcases, transmissions, hydraulic brake systems, and other machinery that requires a fixed minimum amount of liquid during operation.

BACKGROUND ART

As is well known in the art, a minimum amount of liquid is required for reliable operation of many dif¬ ferent types of machinery. For lubrication of engines and transmissions, sufficient oil must be supplied to bearings, gears and other mating parts during operation. Likewise, hydraulic systems such as brakes, clutches, and transmissions require a sufficient fluid reserve during operation. The art of automatic fluid level maintainers comprises various specialized types of apparatus for maintaining a constant level of fluid. Common to many of these types of devices is a system consisting of a sealed air-tight upper reservoir of fluid; and a verti¬ cal passageway at the base of the reservoir through which the fluid may travel to a lower reservoir exposed to atmospheric pressure and having a horizontal passage¬ way near its base to allow fluid to travel to its destination. The elevation of the lower extremity of the vertical passageway determines the minimum level that the fluid will maintain, since any diminution of this level by flow of fluid out of the lower reservoir through the horizontal passageway results immediately in a breaking of the oil seal at the base of the vertical passageway, allowing air to rise through the vertical passageway, which in turn displaces a sufficient volume of fluid downward, raising the fluid level in the lower reservoir again to the base of the vertical passageway to seal it.

One version of this type of maintainer is used to maintain the level of oil in a crankcase of an engine at a fixed minimum level while the engine is not running. This type of device makes use of the splash circulation and lubrication system of the engine to provide a seal of the atmospheric passage to the lower reservoir while the engine is in operation, thus preventing oil from escaping from the upper reservoir to the lower reservoir, even though the average level of the oil in the lower reservoir may be below the lower extremity of the vertical passageway.

Another version of this type provides a second vertical passageway from the upper reservoir to the lower reservoir. The upper extremity of this second passageway enters the sealed upper reservoir at its uppermost point. The lower extremities of both first and second vertical passageways are at the same elevation, said elevation setting the minimum level of the fluid. The second vertical passageway thus provides an additional passage between reservoirs such that when the fluid level drops below the level set by the lower extremities of the vertical passageways, air immediately enters the upper reservoir more easily through the second vertical passageway, forcing fluid through the first vertical passageway of sufficient volume to again seal off both vertical passageways. Other versions of this type provide specialized mechanical designs. One of these versions provides a plunger in the upper reservoir to force liquid from upper reservoir through the lower reservoir and out through the horizontal passageway. By retracting the plunger base to the top of the upper reservoir, oil is drawn in from the lubrication housing for examination through the transparent walls of the upper reservoir. Another version is designed such that the upper reser¬ voir rests hingedly upon the lower reservoir top with a threaded collar ring providing attachment of the upper reservoir to a threaded flange of the lower reservoir. The upper reservoir is filled by removing the collar ring and pivoting the upper reservoir about its hinge 180 degrees, then returning it full of oil to its closed position. Still another version is used to pro¬ vide a constant level of oil for lubricating a pump. An elongated piece of porous material with one end immersed in the oil carries the oil by capillary action to its other end which is adjacent to a lubricating entry point for the pump. When the pump is operating, a vacuum causes air to blow oil off the porous material into the lubrication area. The rate of oil usage is determined by the rate of capillary action. The im¬ mersed end of the porous material remains immersed in a constant level of oil maintained by means herein generally described for this type of system. Some of the major problems inherent in the current apparatus include: a. Those types of liquid level maintainers that rely on splash circulation and lubrication to also maintain a fluid seal of the vertical passageway are inconsistent in maintaining a constant level of fluid. Some engines are maintained in running operation over prolonged periods, but only when the engine is not running is there assurance that a constant level will be maintained with this type of maintainer. All too often, the degree of splash received at the vertical passageway is a function of the RPM of the engine. As a result, either an excess or a deficiency of fluid may be available for the machinery. b. Dual-line systems, or those liquid level maintainers with dual vertical passageways joining upper and lower reservoirs present a number of problems. The addition of a second vertical passageway introduces another potential air-leak path, thus reducing the probability that the upper reservoir and vertical pass¬ ageways will be maintained air-tight. This is a necessity to prevent the upper reservoir from "dumping", i.e., inadvertently draining its contents and overfill¬ ing the lower reservoir. A second problem is also inherent in this type of system. Since the fluid in the second vertical passageway will seek the same level as the fluid level in the upper reservoir because both surfaces are subjected to the same near-vacuum pressure, dirty or contaminated fluid may be drawn up into the second vertical passageway. The fluid level in the upper reservoir is assumed to be below the upper entry point of the second vertical passageway. However, if the fluid level is indeed high in the upper reservoir, it is possible for dirty or contaminated oil to spill over into the upper reservoir. c. The problems inherent in specialized designs of liquid level maintainers are economical in nature. Since their use is restricted to single applications: i.e., special types of bearings, pumps, and reser¬ voirs; it becomes uneconomical to provide different types of liquid level maintainers, for every separate application.

The solutions to the above-listed problems are given in the DISCLOSURE OF INVENTION section. The prior art searched did not disclose any patents or publications that were directly related to a universal fluid level maintainer of the type disclosed herein. However, the following U.S. patents were considered in the investigation and evaluation of the prior art relative to the existing apparatus used with the invention:

PATENT NUMBER INVENTOR ISSUED

3,983,958 Swearinger October 5, 1976 2,564,231 Pitney August 14, 1951 2,564,230 Pitney August 14, 1951 2,460,814 Duerr February 8, 1949 2,041,920 Gits May 26, 1936

The Swearinger patent describes an apparatus with an upper and lower chamber providing plunger means for allowing observation of lubricating oil in a bearing housing, ascertaining the level of oil in the bearing housing, and maintaining a desired fluid level in the bearing. The Pitney patents describe various types of splash circulation type liquid level maintainers, adapted particularly to maintaining the level of oil in a crankcase at a constant level. Duerr discloses a specialized pump lubricating means that supplies a constant rate of lubricating oil to the pump,

OMFI independent of the degree of vacuum developed by the pump, said oil traveling by capillary action on an elongated piece of porous material with one end immersed in a constant level oil reservoir. Gits describes a combined fluid indicator and oil reservoir having a hinged means whereby the lubricator may be replenished with oil with a minimum amount of time and labor.

DISCLOSURE OF INVENTION

The Universal Fluid Level Maintainer is adaptable for automatically maintaining a fixed minimum amount of fluid in automotive vehicle crankcases, transmissions, hydraulic brake systems and other machinery requiring a minimum reservoir of fluid during operation. Because of its simple construction, it is not limited to any one of the above applications, but may be applied to any or all of them. The system is designed to cooperate with an air-tight upper reservoir {or supply tank) and a lubrication housing, oil pan, or other type of lower reservoir exposed to atmospheric pressure. Both upper or lower reservoirs are remote to and are not to be considered part of the invention.

The Universal Fluid Level Maintainer consists of the following parts: a vertically-oriented hollow cylinder called the body, of optional length and cross- section, and having three apertures, one at its upper end, one at its lower end, and one on the vertical wall near the upper end, this latter aperture being called the vent; a vertically-oriented hollow cylinder called the probe, of diameter small enough to be inserted into the upper aperture of the body, having both ends open, and of length such that when its lower end is inserted into the body to a distance below the vent and above the lower aperture of the body, its upper end will extend above the upper aperture of the body; an air-tight sealing and anchoring means at the upper end of the body for maintaining the probe stationary within the body such that its lower end is at a desired dis¬ tance from the lower end of the body but below the vent; an upper fluid feeder conduit having air-tight walls used to connect the lower exit port of an upper fluid reservoir to the upper end of the probe; a lower fluid feeder conduit having air-tight walls used to connect the lower entry port of a lower fluid reservoir to the lower aperture of the body; air-tight connecting and sealing means used to connect the upper fluid feeder conduit both to the upper reservoir exit port and to the probe; air-tight connecting and sealing means used to connect the lower fluid feeder conduit both to the lower reservoir entry port and to the lower aperture of the body; and means for mounting the body in a vertical position such that the lower tip of the probe will be at the desired- operating level of the fluid in the lower reservoir. The lower end of the probe is adjusted to be at the desired fluid operating level. When the level of fluid in the lower reservoir (i.e., engine or transmis- ^•sion oil pan or brake fluid reservoir) drops below the pre-determined level of the tip of the probe within the body, air bubbles flow up through the probe and into the vacuum space above the fluid level in the upper reservoir. This causes an equal amount of fluid in the upper reservoir to flow downward through the upper conduit, the probe, the body, and through the lower fluid feeder conduit to the lower reservoir. When sufficient fluid has caused the level in the body to cover the lower tip of the probe, the flow ceases. This action is repeated any time the probe tip is exposed to atmospheric pressure, thus causing the fluid in the body and lower reservoir to remain at a constant and equal level. The vent exposes the body to atmospheric

OMΪ pressure, to allow maintenance of equal levels of fluid in the lower reservoir and the body. If the pressure in the lower fluid reservoir is other than atmospheric pressure, suitable conduit and air-tight connecting means may be used to connect the vent directly to an entry port in the lower fluid reservoir above the oper¬ ating fluid level.

The solutions to problems inherent in the current apparatus listed in the BACKGROUND ART section follow — each letter preceding the solution corresponding to the noted problem letter: a. Because of the isolation of the invention from the serviced lower reservoir by way of the fluid feeder conduit, no turbulent effect of a splash circula- tion and lubrication system is experienced at the probe tip. Rather, the level of fluid in the body is main¬ tained at the average level occurring within the lower reservoir. b. A single path connects the upper reservoir and the body of the invention. Possibilities of air leaks are considerably reduced. c. The invention is adaptable to nearly every conceivable system requiring a minimum liquid level ^* maintenance, since the invention is isolated from both reservoirs, and may be remotely located to accommodate space requirements.

BRIEF DESCRIPTION OF DRAWINGS

The details of the invention are described in connection with the accompanying drawings in which:

FIGURE 1 is a system operational drawing illus- trating the invention maintaining a constant fluid level in a lower reservoir utilizing fluid supplied

. from an upper reservoir.

FIGURE 2 is a detailed plane view of the preferred embodiment of the invention.

FIGURE 3 is a top view of the body of the invention.

FIGURE 4 is a partial lower side view of the body of the invention.

FIGURE 5 is a plane view of the probe of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The Universal Fluid Level Maintainer 10 is described in terms of the best mode (preferred embodi¬ ment) of the invention and is depicted in FIGURES 1 through 5. The Universal Fluid Level Maintainer 10 is best described by referring to FIGURE 1. The invention comprises a body 20; a probe 30; an upper threaded bushing 40; a lower threaded bushing 50; a vent 60; a mounting bracket 70; a flexible hose 80; a first air- tight hose 81; and a second air-tight hose 82.

Referring to FIGURE 2 in the best mode, the body 10 is constructed using 1 inch (25.4 mm) square tubing that is completely sealed by end sections 21 and 22 at top and base of the body, respectively. The square cross-section is not requisite for the functioning of the invention, but provides a more adaptable form factor for mounting the body in available space. Three circular openings are provided in the body: (a) a 3/8 inch (95.3 mm) diameter hole 23 is provided on the top of the body, (b) a 1/8 inch (31.8 mm) diameter hole 24 is provided on a side near the body base, and (c) a 1/4 inch (63.5 mm) diameter hole 25 is provided on one side, approximately 1 inch (25.4 mm) down from the body top.

O-.^a. An upper threaded bushing 40 of diameter slightly smaller than hole 21 is permanently attached to the top of body 20, concentrically aligned with hole 23. Similarly a lower threaded bushing 50 of approximately the same diameter as bushing 40 is concentrically aligned with hole 24 and permanently attached to the surface of body 20 at this location. Air-tight attach¬ ments are provided for both bushings 40 and 50 at their respective surfaces. FIGURES 3 and 4 illustrate top views of bushings 40 and 50 as mounted on top and side, respectively of body 20. Vent 60 is a circular tube of approximately 1-1/4 inch (31.75 mm) length and diameter slightly larger than hole 25. Vent 60 is lipped or provided with an enlarged outer diameter 61 at one end to accom¬ modate attachment of a flexible hose 80, as illustrated in FIGURE 1. The other end of vent 60 is cut at an approximate 45 degree angle for attachment at that angle to a side wall of body 20 over hole 25. An air-tight seal is provided at the attachment of vent 60 to body 20.

FIGURE 5 illustrates a plane view of probe 30. It is constructed by permanently attaching a male- threaded hollow adapter 31 to one end of a circular tube 32. The outer diameter of tube 32 is such that it fits snugly into the inner walls of adapter 31. An air-tight seal is provided at the attachment of adapter 31 and tube 32. The male threads of adapter 31 that are adjacent to tube 32 mate with the female threads of upper bushing 40. The length of tube 32 is chosen such that when the probe 30 is inserted into hole 23 and screwed into upper bushing 40, the lower tip of tube 32 is approximately half the distance between vent 60 and lower bushing 50. A sealing compound may be used on the.threads of bushing 40 to provide an air¬ tight seal when probe 30 is secured in body 20.

OM?l Operation of the Universal Fluid Level Maintainer 10 is best described by reference again to FIGURE 1. The invention 10 is mounted with mounting bracket 70 to an appropriate reinforcement in a vertical position such that the lower tip of the probe 30 is at the desired level 95 of the fluid in lower reservoir 100. Air-tight hose 81 is attached to the exposed threaded end of probe 30 and to the drain port fitting 91 of upper reservoir 90. Fitting 91 is also normally equipped with a valve 92. This will allow replenishment of fluid in upper reservoir 90 through sealed cap 93 while the invention 10 is connected. Air-tight hose 82 connects lower threaded bushing 50 of body 20 to the lower fluid reservoir 100. Hose 80 may be used to connect vent 60 to air chamber 97 if air pressure in chamber 97 which is exerted on fluid in lower reservoir 100 is different from atmospheric pressure available at 96.

Lower reservoir 100 may be an engine or transmis¬ sion oil pan, a brake fluid reservoir, or other supply of fluids that is required to be maintained at a con¬ stant level during operation. Whenever the level of fluid in the lower reservoir 100 drops below the level 95 of the tip of the probe 30 within the body 20, air bubbles will flow up through the probe 20 and into the vacuum space above the fluid level in the upper reser¬ voir 90. This causes an equal amount of fluid in the upper reservoir 90 to flow downward through hose 81, probe 30, body 20, and through the lower hose 82 into lower reservoir 100. When sufficient fluid has caused the level in the body 20 to cover the lower tip of probe 30, flow from upper reservoir 90 will cease.

This action will be repeated whenever the tip of probe 30 is exposed to the pressure at vent 60. Turbulent flow may possibly be taking place within lower reservoir 90, depending upon the particular utilization or application. Sufficient isolation is provided in body 20, however, from any turbulent action in lower reservoir 100, since the flow rate of fluid between body 20 and reservoir 100 is restricted by the 1/8 inch (31.8 mm) diameter of aperture 24 at the exit point of fluid from body 20 to reservoir 100. Because of this isolation, the average level in reservoir 100 will tend to be maintained at the tip of probe 20.

OMP

Claims

1. ,A Universal Fluid Level Maintainer for maintaining a minimum fluid level in a lower fluid reservoir by transferring fluid into a drain port of , the lower reservoir from a drain port of an air-tight upper fluid reservoir, comprising: a) an outer container, completely sealed except for an upper aperture at its top, a lower aperture in the vicinity of its base, and a middle aperture located on a side wall of the container be¬ tween the upper aperture and the lower aperture; b) a hollow cylinder of diameter small enough to be inserted into the upper aperture of the outer container, the cylinder having both ends open and of sufficient length such that when it is inserted through the upper aperture of the outer container to a distance ^"below the middle aperture and above the lower aperture, its upper end will extend above the upper aperture of the outer container; c) an air-tight sealing and anchoring means for maintaining the hollow cylinder in a fixed position when it is partially inserted into the upper aperture of the outer container, and for providing an air-tight seal at the upper aperture of the outer container when hollow cylinder is thus inserted; d) an upper fluid conduit having air-tight walls and air-tight end connectors, for providing an air-tight connection between the drain port of the upper fluid reservoir and the upper end of the hollow cylinder; and e) a lower fluid conduit for providing a connection between the drain port of the lower fluid reservoir and the lower aperture of the hollow cylinder.

OMPI

2. The apparatus as recited in claim 1, further comprising means for maintaining the outer container in a fixed position.

3. The apparatus as recited in claim 1, wherein the air-tight sealing and anchoring means consists of circular male threads on the outer upper walls of the hollow cylinder, mating circular female threads in the upper aperture of the outer container, and threadsealing compound, so that the hollow cylinder is screwed into the upper aperture of the outer container and secured in the desired position.

4. The apparatus as recited in claim 1, wherein the upper fluid conduit contains a manually-operable valve for controlling rate of fluid flow between the upper fluid reservoir and the hollow cylinder.

5. The apparatus as recited in claim 1, wherein the lower fluid conduit contains a manually-operable valve for controlling rate of fluid flow between the outer container and the lower_^ fluid reservoir.

6. The apparatus as recited in claim 1, further comprising an air hose for providing an air path between the air chamber in the lower fluid reservoir and the middle aperture of the outer container; means for con¬ necting the air hose to the middle aperture of the outer container; and means for connecting the air hose to the air chamber in the lower fluid reservoir.

7. The apparatus as recited in claim 6, wherein the means for connecting the air hose to the middle aperture of the outer container consists of a hollow tube extension of the middle aperture of the outer container, the hollow tube extension inner walls being continuous with the inner walls of the outer container and the hollow tube extension outer walls fitting tightly into the inner walls of the air hose.